Encoders



Dec. 6, 1966 G. HORVATH 3,290,572

ENCODERS Filed Aug. 19, 1963 2 Sheets-Sheet l Dec. 6, 1966 x G. HORVATH 3,290,672

ENCODERS Filed Aug. 19, 1965 2 Sheets-Sheet 2 United States Patent O 3,290,672 ENCODERS Gyula Horvath, Londen, England, assigner to Rotax Limited, London, England Filed Aug. 19, 1963, Ser. No. 303,023 4 Claims. (Cl. 340-347) This invention relates to encoders for providing a digital electrical signal representing the angular position of an encoding member.

An encoder in accordance with the invention comprises a body having therein a cyclindrical bore, a cyclindrical encoding member coaxially mounted in the bore for rotation relative to the body, a light source supported by the body within the encoding member, a row of light sensitive devices extending longitudinally along the wall of the bore, and a lens supported by the body for directing light from the source through the encoding member to energize the light-sensitive devices in a combination determined by the angular position of the encoding member.

In the accompanying drawings, FIGURE l is a sectional side view illustrating one example of the invention, FIGURE 2 is a section on the line 2-2 in FIGURE 1, and FIGURE 3 is a fragmentary view illustrating a modification.

Referring to FIGURES l and 2, there is provided a multi-part body adapted for connection to a fixed sup port 11. The body includes an outer cylindrical member 12 defining a cylindrical bore 13, an inner cylindrical member 14 within the bore and dening with the member 12 an annular space 15 within the bore 13, and an end member 16 closing one end of the bore 13 and incorporating a plurality of terminals 17 arranged in a circular row.

Within the space is a cylindrical encoding member 18 which is secured to a shaft 19 connected to the body 11 by bearings 21 so that the encoding member is rotatable about the axis of the bore 13. Moreover, extending axially along the axis of the bore 13 is a light source 22 which at one end is supported by a part 23 secured to the member 16, and at its other end is supported by a spring contact 24. The Contact 24 has three arms engaging an electrically conductive plate 25 carried by, but insulated from, a plate 26 detachably secured to one end of the member 14.

Extending axially along the inner wall of the member 12 is a cylindrical member 36 having a circuit printed thereon. The member 36 has a brass plate 37 secured thereto, and supported by the brass plate are a row of photocells or other light sensitive devices 27. Moreover, between the source 22 and the row of devices 27 the member 14 is formed with a bore extending parallel to the axis of the bore 13. Within the bore in the member 14 is accommodated a cylindrical lens 28 which serves to direct light from the source 22 onto the devices 27. As can be seen in FIGURE 2, the lens 2S is formed with a pair of diametrically opposite grooves extending inwardly from its periphery. Light passes to the devices through the space between the inner ends of these grooves, so that the angular positions of the lens 28 determines the lens aperture.

The end of the source 22 supported by the part 23 is connected to one of the terminals 17 through the member 16 and an associated conductor (not shown), and an electrical conection to its other end is made by way of a lead 29 extending from, one terminal 17 through the member 14 and connected to the plate 25. Electrical connections to the devices 27 are made through leads (not shown) extending from the terminals 17 through arcuate slots 31 in the member 14 into the space 15 and thence to the devices 27 by way of the member 36. In the example illustrated, one of the terminals 17 is not utilized.

The encoding member 13 is formed on its surface with transparent and opaque sections arranged in accordance with a predetermined code, and the arrangement is such that in use the devices 27 are illuminated in combinations which depend on the angular position of the member 18.

In the modification shown in FIGURE 3, the source 22 is replaced by a solid state light source 32. This source, which conveniently consists of gallium arsenide, can be operated by electrical pulses to produce pulses of light. The source 32 is supported by a block 33 having a pair of electrically conductive end caps 34, 35 which are in electrical contact with the source and with the contact 24 and part 23, respectively.

In a modification (not shown) of either example, the member 14 is considerably thinner radially, and is formed with a slot the sides of which engage in the grooves in the member 28 to hold the member 28 in position. In this case the grooves do not vary the lens aperture.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An encoder comprising a body having an outer member dening therein a cylindrical bore and an inner member within the bore spaced from the outer member, a cylindrical encoding member coaxially mounted in the bore for rotation relative to the body passing through the spacing between said inner and outer members, a light source supported by the body within the inner member to direct light through the encoding member, a row of light sensitive devices extending longitudinally along the wall of the bore and carried by the outer member, and a lens supported by the inner member of the body for directing light from the source through the encoding member to energise the light-sensitive devices in a combination determined by the angular position of the encoding member.

2. An encoder as claimed in claim 1 in which the lens is cylindrical and extends parallel to the axis of the bore, the lens having a pair of diametrically opposite grooves extending inwardly from its periphery, and being so oriented that light from the source passes through the space between the inner ends of the grooves to said devices.

3. An encoder as claimed in claim 2 in which said inner member has therein a slot, the sides of which engage in the grooves to hold the lens in position.

4. An encoder as claimed in claim 2 in which said inner member has therein a bore in which the lens is accommodated, the grooves enabling the lens aperture to be varied by varying the angular setting of the lens in the bore.

References Cited by the Examiner UNITED STATES PATENTS 2,431,591 11/ 1947 Snyder 177-351 2,921,204 1/ 1960 Hastings 250-219 2,957,044 10/ 1960 Calder et al. 178-7.6 3,102,201 8/ 1963 Braunstein et al 250-199 3,166,623 1/ 1965 Waidelich 88-1 3,205,364 9/ 1965 Pong 250-208 3,209,346 9/ 1965 Litte 340-347 DARYL W. COOK, Acting Primary Examiner. MALCOLM A. MORRISON, Examiner. A. L. NEWMAN, Assistant Examiner. 

1. AN ENCODER COMPRISING A BODY HAVING AN OUTER MEMBER DEFINING THEREIN A CYLINDRICAL BORE AND AN INNER MEMBER WITHIN THE BORE SPACED FROM THE OUTER MEMBER, A CYLINDRICAL ENCODING MEMBER COAXIALLY MOUNTED IN THE BORE FOR ROTATION RELATIVE TO THE BODY PASSING THROUGH THE SPACING BETWEEN SAID INNER AND OUTER MEMBERS, A LIGHT SOURCE SUPPORTED BY THE BODY WITHIN THE INNER MEMBER TO DIRECT LIGHT THROUGH THE ENCODING MEMBER, A ROW OF LIGHT SENSITIVE DEVICES EXTENDING LONGITUDINALLY ALONG THE WALL OF THE BORE AND CARRIED BY THE OUTER MEMBER, AND A LENS SUPPORTED BY THE INNER MEMBER OF THE BODY FOR DIRECTING LIGHT FROM THE SOURCE THROUGH THE ENCODING MEMBER TO ENERGISE THE LIGHT-SENSITIVE DEVICES IN A COMBINATION DETERMINED BY THE ANGULAR POSITION OF THE ENCODING MEMBER. 